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Updated: Aug 6, 2026

Ammonia Synthesis at Low Pressure
Published on: August 23, 2017
Atmospheric Pressure Ammonia Synthesis via CO2-Coupled Hydrogenation
Kai Feng1,2, Shuairen Qian1, Xiaozhi Liu3
1Department of Chemical Engineering, Tsinghua University, Beijing100084, China.
None:
The Haber-Bosch ammonia synthesis is a cornerstone of global agriculture and the chemical industry, yet it is fundamentally constrained by intrinsic scaling relations, necessitating energy-intensive conditions associated with a significant carbon footprint. Herein, we report a surface redox-mediated chemical looping strategy that utilizes the CO2 hydrogenation reaction as a chemical trigger to drive ammonia synthesis at atmospheric pressure over a cobalt-molybdenum bimetallic nitride (Co3Mo3N) nitrogen carrier. Mechanistic investigations reveal that CO2 induces a dynamic surface oxidation that weakens the intrinsic Mo-N bonds and facilitates the hydrogenation and release of lattice nitrogen as NH3. The cycle is closed by a subsequent nitridation step that removes surface oxygen and regenerates the nitride lattice. This redox-mediated mechanism enables an unprecedented NH3 peak concentration of ∼2.3% and a release rate of 12.4 mmol·gcat-1·h-1 at 500 °C under atmospheric pressure, circumventing the thermodynamic limitations that historically hinder low-pressure ammonia synthesis. Our findings demonstrate how dynamic surface engineering can decouple kinetic limitations from thermodynamic constraints, offering a novel paradigm for sustainable nitrogen fixation coupled with carbon utilization.
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